Photographic processes for producing prints by transfer and products useful in connection therewith



Apnl 3, 1956 E. H. LAND 2,740,715

PHOTOGRAPHIC PROCESSES FOR PRODUCING PRINTS BY TRANSFER AND PRODUCTSUSEFUL IN CONNECTION THEREWITH Filed Oct. 10, 1952 Supporf lOa Ph I H"Phofosensifive lo 0 osens we Emulslon P Silver Precipirufing flmg Layerl6 Composih'on zprinf Receiving Elemenf Supporf I20 INVENTOR ATTORNEYSUnited States Patent PHOTOGRAPHIC PROCESSES FOR PRODUCING PRINTS BYTRANSFER AND PRODUCTS USE- FUL IN CONNECTION THEREWITH Edwin H. Land,Cambridge, Mass, assignor to Polaroid Corporation, Cambridge, Mass acorporation of Delaware Application October 10, 1952, Serial No. 314,053

25 Claims. (Cl. 95-8) This invention relates to photographic productsand processes and more particularly to transfer processes which involvethe development of a latent image in a silver halide emulsion and thetransfer of components rom said emulsion to another layer to effect theformation of a print of said latent image in said other layer, and toproducts useful in the performance of said transfer processes.

It has been proposed to carry out transfer processes with aphotosensitive element comprising a silver halide emulsion layer bydistributing a processing composition in a thin layer between saidelement and another element, the latter element preferably serving toreceive the transfer print. Processes of this type are characterized bythe fact that the processing composition which is distributed layerwiseconstitutes the sole source of liquid for the processing operation andis essentially confined between the outer surfaces of the superposedelements throughout the processing.

In the performance of these processes, the processing composition eithercontains the developing agent prior to its distribution or dissolvessuch an agent after it is distributed, and, in either event, theprocessing composition renders the developing agent effective fordeveloping the silver halide emulsion. When using most developingagents, it must be relatively highly alkaline to perform this function.A highly alkaline environment is thus pro duced in the print-receivinglayer, and this environment, if permitted to exist, sometimes introducesseveral sources of instability which adversely affect the pictorialquality of the print with the passage of time. A principal source ofthis instability is the oxidation of the unexhausted residue developerwhich may stain the highlights of the print-receiving layer. Theoccurrence of this instability is reduced to negligible proportions ifthe alkalinity of the print-receiving layer can be effectively loweredwithin a relatively short time after the formation of the transfer printtherein.

lt is accordingly one object of the present invention to provide animproved process for forming prints, by transfer, wherein a developingcomposition of relatively high alkalinity may be used during the printformation but which gives afinished transfer print whose ultimatealkalinity is low enough to substantially eliminate .the possibility ofthe aforementioned print instability. This object is achieved byproviding, preferably on or adjacent to the surfaces of the elementspermeated by the processing liquid, compounds which will react with theby droxyl ions of an alkaline solution to produce a volatile reactionproduct which itself is alkaline. As a result, during the creation ofthe transfer print, the processing composition remains alkaline despitethe formation of the said reaction product. However, when the twosuperposed elements are stripped apart, the volatile reaction productbecomes free to evaporate from the positive print, thereby effectivelyreducing the alkalinity of the positive'print. It is more convenient tohave the alkali element 10 and a present initially in the composition ina nonvolatile condition and to avoid any volatilization of the alkalinecomponent until after the final print is obtained and both thesedesirable objectives are achieved by the aforementioned arrangement.

One class of stabilizing agents comprehended by the present inventionare the salts of the volatile amines and particularly of amines whichare aliphatic and whose one normal solution has a pH in excess of 10.The salts of the more volatile amines, i. e., amines having a boilingpoint of the order of C. or less, are of course preferred, and examplesof such amines whose salts are satisfactory are diethylamine,triethylamine, diisopropylamine, allylamine and ethylamine. Thehydrochlorides, sulfates, nitrates, oxalates, citrates and tartrates ofthese amines may be satisfactorily employed, and preferred species ofsalts are diethylamine hydrochloride, diethylamine sulfate, anddiethylamine nitrate.

The reduction in the alkalinity in the print-receiving layer which isthe result of the novel use of the aforementioned products may besupplemented by the use of acidifying agents, such as metallic salts ororganic compounds which react in alkaline solution to consume alkali, orvarious mixtures thereof. Materials of this general type and useful forthis purpose are disclosed in my United States Patent No. 2,584,030issued January 29, 1952 for Light-Sensitive Silver Halide PhotographicProduct for Image Transfer and Process Utilizing the Same and in mycopending application Serial No. 37,252, filed July 6, 1948, forPhotographic Product and Process.

These and other objects of the invention will in part be obvious andwill in part appear hereinafter.

The invention accordingly comprises the product possessing the features,properties and the relation of components, and the process involving theseveral steps and the relation and order of one or more of such stepswith respect to each of the others, which are exemplified in thefollowing detailed disclosure, and the scope of the application of whichwill be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing wherein:

Figurel is a diagrammatic, enlarged, sectional view illustrating theassociation of elements during one stage of the performance of one formof the novel transfer process of the invention, the thicknesses of thevariousmaterlals being exaggerated and not necessarily in correctrelative proportion; and

Fig. 2 is a perspective view, with parts broken away, of one form ofprint-receiving element upon which containers of. the processing agentare so positioned as to be capable of distributing their contentsbetween the surface of the print-receiving element and a photosensitiveelement.

The present invention comprehends improved processes and products of thetype whereby a positive print may be obtained in a single step bysuitably treating a silver halide emulsion containing a latent imagewith a uniformly applied layer of processing liquid. Preferably, theprocessing composition is in a viscous condition and is spread in aliquid film 14 (Fig. 1) between the photosensitive print-receivingelement 12. The photosensitive element, as shown, comprises a support10a and a silver halide emulsion 10b and the print-receiving element ispreferably of a type suitable for receiving silver transfer prints andcomprises a support 12a upon which is mounted a silver precipitatinglayer 16. In this form of the process, the liquid composition developsthe latent image in the emulsion and forms a soluble silver complex withundeveloped silver halide. This soluble silver complea is at least inpart transported in the direction of print-receiving element 12 and thesilver thereof is largely precipitated in the silver precipitating layer16 to form a positive image in silver.

The novel stabilizing agents comprehended by the present invention arecarried by one or both of elements 10 and 12, being dispersed in theportions of said elements which are permeated by the liquid of theprocessing composition. Where the support 12a of element 12 is permeableto the processing composition and is not separated from the silverprecipitating layer 16 by an impermeable subcoat, it is preferable tohave the stabilizing salts dispersed throughout the thickness of saidsupport 12a. On the other hand, if support 12a is formed of a relativelyimpermeable material or has its surface coated with such a material, thestabilizing salts may be carried by a subcoat provided beneath silverprecipitating layer 16. The stabilizing agent may also be dispersedthroughout the emulsion layer 10b or carried in a permeable subcoatlocated between said emulsion layer and its support.

When provided in the photosensitive element either in layer 10b or in anadjacent layer, consideration should be given to the possible effect ofthe stabilizing agent upon the sensitivity of the emulsion. In thisconnection the amine sulfates are preferred to the correspondinghydrochlorides, especially when layer 10b is one of the relatively fastsilver halide negative type emulsions. In all of the foregoingalternatives a sufficient excess of the stabilizing salt is preferablyprovided to assure reaction with the entire hydroxyl content of theprocessing composition.

It has been proposed to use in the silver precipitating layer certaincompounds and elements Whose presence during the transfer process has adesirable effect on the amount and character of the silver precipitatedduring image formation. For this purpose such materials as, for example,metallic sulfides and selenides, thiooxalates and thioacetamides havebeen disclosed in my copending applications Serial No. 7795, filedFebruary 12, 1948 for Photographic Process, Serial No. 164,908, filedMay 29, 1950 for Photographic Silver Halide Transfer Product and Processand Serial No. 727,385, filed February 8, 1947 for Photographic Productand Process. Other precipitating agents have been proposed, such as thecolloidal metals and specifically colloidal silver. It is alsodesirable, as disclosed in the said copending applications, to provide,as the vehicle for the silver precipitating agents in layer 16, amacroscopically continuous film that consists of submacroscopicagglomerates of minute particles of a suitable, water-insoluble,inorganic, chemically inert,

adsorbent, preferably siliceous, material, such, for example, as silicaaerogel. The use of such a vehicle for the precipitating agents tends toaggregate the silver that is precipitated into its most effective formfor print making.

As noted hereinabove, the processing composition is preferably viscousand has dispersed therein, usually in solution, a sufficient amount ofsolid film-forming thickening agent for imparting thereto its desiredviscosity. By suitably selecting the film-forming thickening agent andtreating the surfaces of the print-receiving element and/or thephotosensitive element, it becomes possible to strip the essentiallysolid film, which is the residue of the processing composition, witheither of said elements. In general, this solid residual film willadhere to the printreceiving element. However, there have been disclosedin my aforementioned copending application, Serial No. 7795, varioustypes of processing compositions and methods of treating the surfaces ofthe print-receiving element and/or the photosensitive element so thatsaid solid residual film adheres to the photosensitive element as thelatter is stripped from the print-receiving element.

It is also possible to dispense with the silver precipi' tating layer 16as such and to provide suitable silver precipitating agents in theprocessing composition so that the silver is essentially precipitated insaid composition. This may be accomplished, for example, in the mannerdisclosed in my copending application, Serial No. 88,832, filed April21, 1949, for Photographic Transfer Processes and Products andCompositions for the Practice of Said Processes. In the latter type oftransfer process, it is preferable that the residual film, obtained fromthe processing composition and in which the transfer print is formed,adhere to support 12a as the latter is stripped from the photosensitiveelement 10.

To provide the desired control of the alkalinity of the print-receivingelement, subsequent to the formation thereon of the transfer print,there is preferably included in element 12 a compound such, for example,as the salt of a volatile amine which reacts with the hydroxyl groups inthe processing composition to form the volatile amine. The latter issufficiently alkaline to maintain the alkalinity of the processingcomposition at its desired high level so long as the concentration ofthe amine is not reduced. However, because of the volatlity of theamine, the latter will evaporate when the printreceiving element isstripped from the photosensitive element, thereby substantially reducingthe alkalinity of the print receiving element. As noted hereinabove,this stabilizing agent can be contained in the support for theprint-receiving element, or in the emulsion layer, or in a separatelayer provided either as a subcoat or overcoat for emulsion layer 10b orsilver precipitating layer 16.

Referring again to Fig. 1, liquid layer 14 may be obtained by spreadingthe processing composition, for example, in a manner disclosed in mysaid copending ap plication Serial No. 7795. Preferably, the processingcomposition contains, in addition to the alkali, the silver halidedeveloper and the material for forming the soluble silver complex withthe undeveloped silver halide, i. e., a silver halide fixer. Thesematerials are preferably in aqueous solution. It is to be understood,however, that the silver halide developer and/or the silver halide fixermay be, in part or wholly, added to the processing composition as orafter it is spread between elements 10 or 12, said reagents being solocated in or adjacent the surface of one or both of said elements as tobe dissolved by or otherwise interacted with the liquid composition whenthe latter contacts said surface.

The liquid processing composition may be provided for spreading as alayer 14 between elements 10 and 12 by being discharged from anelongated rupturable container 20 which, as shown in Fig. 2, has alength at least equal to the transverse dimension of the area ofphotosensitive element 10 to which the liquid processing agent is to beapplied Individual containers may be manually or mechanically fedbetween the print-receiving and the photosensitive elements by mechanismof the type shown in my Patents Nos. 2,435,718 and 2,543,180. One ormore containers 20 may also be attached to one of elements 10 or 12 and,in Fig. 2, two such containers are shown secured to the print-receivingsurface of element 12, being spaced apart, lengthwise of said element, adistance equal at least to the length of a single frame of thephotosensitive element 10. Said elements 10 and 12 may be connectedtogether so that they can be superposed with the container so positionedthat it can release its contents in a film therebetween. The container20 is preferably inexpensive and disposable and so constructed as to becapable of retaining the liquid processing agent or composition thereinfor relatively long periods of time without vapor loss or oxidation. Oneexample of a suitable container of this type is formed from a singlemultilayer sheet of material comprising three laminae. The inner lamiua,which provides the inner surface of the container, is formed of amaterial which is chemically inert to the reagents in the processingagent and which is impervious to the liquid of the agent. One materialsuitable for this purpose is polyethylene. The intermediate lamina ispreferably impervious to the vapor of the processing agent and isformed, for example, of a metallic foil such as lead, aluminum or silverfoil. The outer or backing lamina is formed of a strong, deformable,relatively, inexpensive sheet material such as a kraft paper.

The container 20 is preferably formed by taking the single sheet ofthree-ply material and folding the same medially at 22, and thereaftersecuring the end marginal portions 24 and the longitudinal portions 26of the two folded faces to one another, providing a central space orcavity 28 for containing the processing liquid. The seal provided at thelongitudinal portions 26 is preferably weaker than the end seals,providing a liquid-discharging lip which substantially parallels thelong dimension of the container.

To fill the container it is possible to adhere together the opposite,longitudinally extending, marginal portions 26 and one of the endmarginal portions 24, the container being filled through the other end,which is thereafter sealed.

Photosensitive element maybe any of the commer cially availablephotosensitive silver halide films, the term films being understood toinclude paper-backed emulsions. The products of the present inventionare particularly useful in improving the results obtained when thetransfer process is carried out with one of the highspeed photosensitivesilver halide emulsions such as the emulsion of the relativelyhigh-speed orthochromatic films, e. g., Eastman Kodak Verichrome film,having an A S A speed rating of 0200 and an A S A exposure index ratingin the daylight of 50, and the extremely high-speed panchromaticemulsions, e. g., Eastman Kodak Super XX Pan having an A S A speedrating of 0400 and an A S A exposure index rating in the daylight of100, and Ansco Triple S Pan.

Element 12 may be formed by applying to a suitable support 12a, forexample of baryta paper, a coating of a suspension or sol of the silicacontaining the silver precipitating agent. This sol is permitted to dryand provides layer 16. The suspension of silica may be obtained bydispersing the silica, for example, in water, and then adding the silverprecipitating agent either directly or by introducing into the sol saltswhose reaction product is the precipitating agent. The sol may also beapplied to the sheet without the silver precipitating agent, and thesheet with the layer of silica thereon may then be dipped in a solutionor mixture of the silver precipitating agent to deposit the latter insaid layer.

To provide element 12 with the stabilizing salt, it is preferable tointroduce, into the last bath into which said element is immersed duringits preparation, a highly concentrated quantity of the stabilizing salt.This will permeate support 12a and provide a sufficient reservoir of thesalt to convert essentially all the hydroxyl groups.

As has previously been noted, preferred stabilizing salts are thealiphatic salts of volatile amines. In general, it is important that thealkaline reaction productof the reaction between the said stabilizingsalts and the hydroxyl groups in the processing composition give aslightly lower alkalinity than the alkalinity obtained from the materialwhich introduces said hydroxyl groups into the alkaline solution. It isto be observed, in this respect, that the aliphatic amines, whilesufficiently alkaline to maintain operative a developer composition,possess a slightly lower alkalinity than the alkalinity, for example, ofthe hydroxides of the alkali metals and the alkali earths.

In the event that the support 12a of the print receiving element issubstantially waterproof or is provided with a substantially waterproofcoating adjacent the silver piecipitating layer 16, the stabilizing saltmay be provided in a subcoat which is between layer 16 and support 12aand which is sufiiciently thick to carry an adequate quantity of saidstabilizing salt to obtain the desired result. It is possible, ofcourse, to locate some of the stabilizing salt'in the permeable portionof the photosensitive element and remainder in the print-receivingelement, in which event-a subeoat for the stabilizing agent may besubstantially thinner than if the print-receiving element carried all ofthe stabilizing salts.

Examples of the novel processes and materials of the invention forforming positive transfer prints in silver are given below, but it is tobe expressly understood that these examples are merely illustrative andthat the invention is not limited to the materials or proportions setout therein.

Example 1 A processing composition is prepared by mixing together thefollowing ingredients:

is formed .by immersing the sheet of baryta paper in a A print-receivingelement 12 baryta-coated surface of a mixture comprising:

Silica aerogel (Santocel C) "grams-.. 800 60% water solution of gumarabic ..cc 135 /2 solution of sodium sulfide cc 3,200 Cadmium acetategrams 19 Lead acetate do 25 Water cc 13,400

for approximately ten seconds. As the sheet is withdrawn from themixture, the excess of the mixture is removed from the surface of thesheet by a buffer roll or squeegee. The sheet is then immersed in a bathcomprising:

Water cc 1,000 Diethylamine sulfate "grams-.. 250

until said solution has permeated the support 12a of the lmage-receivingelement. This same solution tends to wash out any excess soluble saltsin the receiving sheet.

The processing composition is spread in a layer of approximately.O02-.003 inch in thickness between the treated baryta surface ofelement 12 and the photosensitive silver halide emulsion 10b ofphotosensitive element 10. Emulsion 10b is a relatively high speedorthochromatic emulsion like the emulsion of Eastman Kodak Verichromefilm and has been exposed to predetermined subject matter so that itcontains a latent image of this subject matter, and support for saidemulsion is a white paper. The lamination formed by the spreading of theprocessing agent in a layer 14 between elements 10 and 12 is kept intactfor approximately one-half to one and one-half minutes, preferably oneminute, and at the end of this time, element 12 is stripped from element10. Element 12, when so stripped, carries a positive print in silver ofthe subject matter of the latent image of. emulsion 10b. in this form ofthe process, the film of sodium carboxymethyl cellulose contained in thelayer 14 of the processing composition adheres to the surface of element12 and solidifies to form a film thereon.

The hydroxyl ions of the processing composition are converted to thevolatile alkaline amine during the processing, and so much of this amineas remains in the print-receiving stratum begins to evaporate shortlyafter the stripping of said print-receiving element from thephotosensitive element so that there is soon produced a sufficientdiminution in the alkalinity of the print-receiving stratum to greatlyminimize the creation of stains and other sources of instability.

Other materials may be substituted for those used in the foregoingprocess and the proportions may be varied to an appreciable extent. Forexample, the film-forming material in the processing agent which impartsthe desired viscosity to the latter may be any of the high molecularweight polymers which are stable to alkalies and which are soluble inaqueous alkaline solutions. For example,

such other plastics as hydroxyethyl cellulose, carboxymethyl-hydroxyethyl cellulose, polyvinyl alcohol and the sodium salts ofpolymethacrylic acid and polyacrylic acid may be used. It is desirablethat the plastic be contained in the agent in sufiicient quantities toimpart to the composition a viscosity in excess of 1000 centipoises at atemperature of approximately 24 C. Preferably the viscosities of theprocessing agent are of the order of 1,000 to 200.000 centipoises at atemperature of approximately 24 C.

Other developing agents may be used, for example one of the following:paminophenol hydrochloride; bromohydroquinone; chlorohydroquinone;diaminophenol hydrochloride; toluhydroquinone; monomethyl-p-aminophenolsulfate; a mixture consisting by weight of one-half hydroquinone andone-half p-hydrorzyphenylaminoacetic acid; and a mixture consisting byweight of one-fourth hydroquinone and three-fourthsp-hydroxyphenylaminoacetic acid.

To form the soluble silver complex, such other complexforming substancesas sodium thiocyanate, ammonium thiocyanate and ammonia may be employed.

Support 12a of element 12 may consist of gelatine, cellophane, polyvinylalcohol, sodium alginate, and cellulose ethers such as methyl celluloseand their derivatives such as hydroxyethyl cellulose.

Other stabilizing salts, such for example as diethylamine hydrochlorideor methylamine hydrochloride, may be used in essentially the samequantity as the diethylamine sulfate of this example.

Example 2 The residual film of carboxymethyl cellulose may be strippedwith the photosensitive element instead of with the print-receivingelement by providing a stripping layer on the surface of theprint-receiving element. This is accomplished by roll-coating on theprocessed printreceiving element of Fig. 1 a 5% aqueous solution ofpolyvinyl alcohol in a layer whose thickness is of the order of .001inch. An equivalent amount of hydroxyethyl cellulose or polymethacrylicacid may be substituted for the polyvinyl alcohol of this example.

As noted hereinabove, the silver precipitating agents which aid in thereduction and precipitation of the metallic silver of the positive printmay be contained in the developer composition. One example of acomposition which can be usefully employed in this manner to therebyavoid the need for a special silver precipitating layer upon theprint-receiving element is the following:

This composition is spread, as in Example 1, between a photosensitiveemulsion of the Vcrichrome type and the baryta-coated surface of a plainbaryta sheet. At he end of approximately a minute, the baryta sheet isstripped from the emulsion and carries with it the solid residue of thespread composition. This solid residue provides the print-receivingstratum. The silver precipitate which produces the positive is formedlargely in this stratum and gives a positive print of good quality, highresolving power and excellent stability.

it is also possible in any of the foregoing examples to have thestabilizing salt provided in part or in whole in the photosensitiveemulsion. One example of an emulsion so constituted is the following:

Example 4 A photosensitive silver halide element comprising a paper baseand a Verichrome type emulsion is dipped into a 5% aqueous solution ofdiethylamine sulfate for five minutes. This photosensitive element isthereafter used in conjunction with a print-receiving element which isformed in the same manner as the print-receiving element of Example 1except that the last dipping operation involving diethylarnine sulfateis omitted. These two sheets are processed, as described in Example 1,with the processing composition of that example to give a transfer printof good quality and stability.

Since certain changes may be made in the above product and processwithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawing shall be interpreted as illustrative and not ina limiting sense.

What is claimed is:

1. A photographic process for forming, by transfer, a print of a latentimage contained in the silver halide emulsion of a photosensitiveelement wherein a single application of liquid to said element iseffective to give a finished print of improved stability, which processcomprises the steps of bringing an alkaline processing compositioncontaining a relatively nonvolatile alkali into contact with thephotosensitive element so as to permeate said emulsion with the liquidof said composition; providing another element in superposed relationwith the photosensitive element so that the said composition is confinedbetween the outer surfaces of said elements, said processingcomposition, upon permeation of said silver halide emulsion, containingreagents for developing said latent image and for forming a transferprint thereof in a print-receiving stratum of the superposed assemblyformed by said elements and said layer of liquid, said reagentsincluding a silver halide developer which is characterized by itspropensity for oxidizing in an alkaline environment and for adverselyaffecting the transfer print when so oxidized in the print-receivingstratum, at least one of said elements containing, in the portionthereof permeated by said processing composition, a salt of an organicamine capable of reacting with the hydroxyl content of said compositionto give, as a reaction product, an organic amine which is alkaline butless alkaline than the said nonvolatile alkali and which is volatile;retaining said photosensitive element and said other element insuperposed relation until the latent image in the sliver halide emulsionis developed and a print of said latent image is formed in saidprint-receiving stratum; and stripping said two elements from oneanother to permit volatilization of the volatile reaction product fromsaid stratum.

2. The process of claim 1 wherein the salt for reacting with thehydroxyl content of the processing composition is a salt of an aliphaticamine.

3. The process of claim 2 wherein the said amine gives a pH in excess of10 in a one normal solution and has a boiling point lower thanapproximately C.

4. The process of claim 1 wherein the processing composition contains athickening agent and is spread be tween said elements and, when sospread, tends to form a solid layer of said thickening agent, said layerof thickening agent providing the print-receiving stratum.

5. The process of claim 1 wherein the processing composition contains athickening agent and is spread between said elements and, when sospread, tends to form a layer of the thickening agent, said layer ofthickening agent adhering to the photosensitive element when the latteris stripped from the other element and a surface :portionrof said otherelement providing the print'reeeiving stratum.

6. A photographic process for forming, by transfer, a positive print ofa latent image contained in the silver halide emulsion of aphotosensitive element wherein a single applicationof liquid to saidelement is effective to give a'finished print of improved stability,which process comprises the steps of bringing a relatively uniformlayerwise distribution of an alkaline processing composition containinga relatively nonvolatile alkali into contact with the photosensitiveelement so as to permeate said emulsion with the liquid of saidcomposition; providing a print-receiving element in superposed relationwith the photosensitive element so that the layerwise distribution ofthe processing composition is essentially confined to said superposedelements, said processing composition containing, after permeation ofsaid silver halide emulsion, all of the reagents, including a silverhalide developer, for developing the latent image in the silver halideemulsion and for forming a positive print of the Subject matter of saidlatent image upon said printreceiviug element, said developer beingcharacterized by its propensity for oxidizing in an alkaline environmentto form stains; reacting the hydroxyl content of said processingcomposition with a salt of an organic amine provided by a permeatedportion of one of said elements to form a volatile amine; retaining saidphotosensitive element and said print-receiving element in superposedrelation until the latent image in the silver halide emulsion isdeveloped and a positive print of the subject matter of said latentimage is formed in said print-receiving element; and stripping saidprint-receiving element with the positive print thereon from saidphotosensitive element, thereby permitting the said volatile amine toevaporate.

7. The process of claim 6 wherein the salt for reacting with thehydroxyl content of the processing composition is a salt of a volatile,aliphatic amine, and the reaction product is the amine.

8. The process of claim 7 wherein the said amine gives a pH in excess ofin a one normal solution and has a boiling point lower thanapproximately 175 C.

9. A photographic process for forming by transfer a positive print of alatent image contained in the silver halide emulsion of a photosensitiveelement wherein a single application of liquid to said element iseifective to give a finished print sufficiently stable to require nosubsequent stabilizing treatments for ordinary use, which processcomprises the steps of spreading in a layer between the photosensitiveelement and another element a processing liquid which includes, insolution, a silver halide developer characterized by its propensity foroxidizing in an alkaline environment to produce stain, a silver halidesolvent, at film-forming thickening agent and, as its principal alkali,a relatively nonvolatile hydroxide; reacting the hydroxyl content ofsaid composition with a salt of a volatile, organic amine to form anamine whose one normal solution has a pH in excess of 10 and whoseboiling point is lower than approximately 175 C.; developing the latentimage in said emulsion and forming a positive print in silver in aprint-receiving stratum provided by one of said elements and said layerof processing liquid; and stripping said elements from one another afterthe formation of a silver transfer print in said printreceiving stratum,thereby exposing to the atmosphere the surface portion of saidprint-receiving stratum which contains said volatile, organic amine topermit said amine to volatilize.

10. The process of claim 9 wherein the processing liquid, when spreadbetween said elements, tends to form a solid layer of the thickeningagent and said layer of thickening agent provides the print-receivingstratum.

11. The proceess of claim 10 wherein the processing liquid, when spreadbetween said elements, tends to form a solid layer of the thickeningagent and said layer of thickening agent adheres to the photosensitiveelement when thelatterisstripped from the otherelement,-asurfaceportion. of said other element providing the printreceivingstratum.

12. A photographic product comprising, in combination, a photosensitive.silver halide layer, another layer, and a container carrying analkaline processing liquid comprising a relatively nonvolatile hydroxideas its alkali, means holding said layers and said container together sothat said container is capable of releasing its-contents to permeatesuperposed portions of said layers, said product containing reagents,including a silver halide developer, which are rendered operable uponthe releaseof said content: to develop a latent image in saidphotosensitive layer and to form in a stratum of :said product otherthan said photosensitive layer a transfer print of said latent image, atleast one ofsaid layers carrying, in the portions thereof adapted to hepermeated by said liquid, a salt of a volatile, organic amine capable ofreacting with said hydroxide to give a volatile, organic amine.

13. The product of claim 12 wherein the salt is a salt of an organicamine having a pH in excess of 10 in one normal solution and having aboiling point lower than approximately C.

14. The product of claim 12 wherein the said salt is carried, at leastin part, by said other layer, and the latter provides the stratum forreceiving the positive print.

15. The product of claim 12 wherein the processing liquid in thecontainer comprises a thickening agent capable of providing theprint-receiving stratum when the container contents are released.

16. The product of claim 12 wherein said salt is contained in thephotosensitive layer.

17. A photographic product comprising, in combination, a photosensitivesilver halide layer, another layer, and a container carrying an alkalineprocessing liquid comprising a relatively nonvolatile alkali, meansholding said layers and said container together so that said containeris capable of releasing its contents to permeate superposed portions ofsaid layers, said product containing reagents, including a silver halidedeveloper, which are rendered operable upon the release of said contentsto develop a latent image in said photosensitive layer and to form in astratum of said product other than said photosensitive layer a transferprint of said latent image, at least one of said layers carrying, in theportions thereof adapted to be permeated by said liquid, a salt of anorganic amine capable of reacting with the hydroxyl content of saidliquid to form a volatile, organic amine.

18. A photographic product for use in the formation of transfer prints,said product comprising a rupturahle containing means holding aphotographic processing liquid and a sheet support upon which saidcontaining means is mounted, said sheet support providing animage-receiving area adjacent said containing means onto which saidliquid is spreadable in a thin layer directly from said containingmeans, said liquid being highly alkaline and comprising as its principalalkal-imparting component a relatively nonvolatile alkali, said supportcarrying, distributed over said image-receiving area, a salt of anorganic amine capable of reacting with the hydroxyl content of theliquid in said containing means to form a volatile, organic amine.

19. The product of claim 18 wherein the said sheet support includes aphotosensitive silver halide emulsion as a stratum thereof.

20. The product of claim 18 wherein the liquid in the containing meansincludes at least one substance from the class consisting of the silverhalide developers and the silver halide solvents.

21. The product of claim 18 wherein the salt is a salt of an aminehaving a pH in excess of 10 in one normal solution and having a boilingpoint lower than approximately 175C.

22. A photographic product capable of forming transfer prints inconjunction with a photosensitive silver halide element, said productcomprising a rupturable containing means holding a liquid and a sheetsupport upon which said containing means is mounted, said sheet supportproviding an image-receiving area adjacent said containing means andonto which said liquid is spreadable in a thin layer directly from saidcontaining means, said product carrying all of the reagents, including astain-forming silver halide developer and an alkali, for forming atransfer print of a latent image in a silver halide emul sion, saidreagents being so located in relation to said image-receiving area thatthe spreading of said liquid over said area disperses the silver halidedeveloper and the other reagents throughout said area in adequatequantity to form a transfer print of a latent image in an area of acontiguous silver halide element equivalent to said image-receivingarea, said support carrying, distributed over said image-receiving layerand in addition to said reagents, a salt of an organic amine capable ofreacting with the hydroxyl content of said liquid to form a volatile,organic amine.

23. The product of claim 22 wherein the salt is a salt of an aminehaving a pH in excess of 10 in one normal solution and having a boilingpoint lower than approximately 175 C.

24. A print-receiving element for having transfer prints formed thereonby reducing the silver of a soluble silver complex brought into contacttherewith, said element being substantially inert to light andcomprising a support and a silver precipitation layer, one surfaceportion of said element including said layer being permeable to theionic content of an aqueous solution of a soluble silver complex, saidlayer comprising a macroscopically continuous matrix of particles of awater-insoluble, inorganic, chemically inert, adsorbent, siliceoussubstance, said matrix having dispersed therethrough solid colloidalparticles of a silver precipitation agent for aiding the reduction andthe precipitation of metallic silver from silver complex ions in thepresence of a developing agent, said surface portion having distributedtherethrough a stabilizing agent, said stabilizing agent being a salt ofan organic amine capable of reacting with the hydroxyl content of analkaline liquid to form a volatile, organic amine.

25. The product of claim 24 wherein the salt is a salt of an aminehaving a pH in excess of 10 in a one normal solution and having aboiling point lower than approximately 175 C.

References Cited in the file of this patent UNITED STATES PATENTS2,011,669 Zehlke Aug. 20, 1935 2,245,236 Trivelli et al. June 10, 19412,352,014 Rott June 20, 1944 2,543,181 Land Feb. 27, 1951 2,698,245 LandDec. 28, 1954 FOREIGN PATENTS 873,507 France Mar. 23, 1942 663,019 GreatBritain Dec. 12, 1951 482,643 Canada -2 Apr. 22, 1952

1. A PHOTOGRAPHIC PROCESS FOR FORMING, BY TRANSFER, A PRINT OF A LATENTIMAGE CONTAINED IN THE SILVER HALIDE EMULSION OF A PHOTOSENSITIVEELEMENT WHEREIN A SINGLE APPLICATION OF LIQUID TO SAID ELEMENT ISEFFECTIVE TO GIVE A FINISHED PRINT OF IMPROVED STABILITY, WHICH PROCESSCOMPRISES THE STEPS OF BRINGING AN ALKALINE PROCESSING COMPOSITIONCONTAINING A RELATIVELY NONVOLATILE ALKALI INTO CONTACT WITH THEPHOTOSENSITIVE ELEMENT SO AS TO PERMEATE SAID EMULSION WITH THE LIQUIDOF SAID COMPOSITION; PROVIDING ANOTHER ELEMENT IN SUPERPOSED RELATIONWITH THE PHOTOSENSITIVE ELEMENT SO THAT THE SAID COMPOSITION IS CONFINEDBETWEEN THE OUTER SURFACES OF SAID ELEMENTS, SAID PROCESSINGCOMPOSITION, UPON PERMEATION OF SAID SILVER HALIDE EMULSION, CONTAININGREAGENTS FOR DEVELOPING SAID LATENT IMAGE AND FOR FORMING A TRANSFERPRINT THEREOF IN A PRINT-REOEIVING STRATUM OF THE SUPERPOSED ASSEMBLYFORMED BY SAID ELEMENTS AND SAID LAYER OF LIQUID, SAID REAGENTSINCLUDING A SILVER HALIDE DEVELOPER WHICH IS CHARACTERIZED BY ITSPROPENSITY FOR OXIDIZING IN AN ALKALINE ENVIRONMENT AND FOR ADVERSELYAFFECTING THE TRANSFER PRINT WHEN SO OXIDIZED IN THE PRINT-RECEIVINGSTRATUM, AT LEAST ONE OF SAID ELEMENTS CONTAINING, IN THE PORTIONTHEREOF PERMEATED BY SAID PROCESSING COMPOSITION, A SALT OF AN ORGANICAMINE CAPABLE OF REACTING WITH THE HYDROXYL CONTENT OF SAID COMPOSITIONTO GIVE, AS A REACTION PRODUCT, AN ORGANIC AMINE WHICH IS ALKALINE BUTLESS ALKALINE THAN THE SAID NONVOLATILE ALKALI AND WHICH IS VOLATILE;RETAINING SAID PHOTOSENSITIVE ELEMENT AND SAID OTHER ELEMENT INSUPERPOSED RELATION UNTIL THE LATENT IMAGE IN THE SILVER HALIDE EMULSIONIS DEVELOPED AND A PRINT OF SAID LATENT IMAGE IS FORMED IN SAIDPRINT-RECEIVING STRATUM; AND STRIPPING SAID TWO ELEMENTS FROM ONEANOTHER TO PERMIT VOLATILIZATION OF THE VOLATILE REACTION PRODUCT FROMSAID STRATUM.